The present invention relates to a vertical magnetic head suitable for recording and reproducing a high density record.
Since the existing magnetic recording mode employing a magnetic head of a ring type utilizes the residual magnetization on the principal surface of a magnetic recording medium, i.e. a surface parallel to the magnetic film surface, when the recording density of signals is increased, the diamagnetic field within the recording medium is increased to cause the damping and rotation of residual magnetization to make the detection of recorded signals difficult or to decrease the S/N ratio of the detected signals.
For such a reason, there has been proposed a recorder having a vertical magnetic recording mode which utilizes the residual magnetization perpendicular to the magnetic film surface of a recording medium and can record by reducing the diamagnetic field when the recording density is increased.
FIG. 1 illustrates an existing vertical magnetic head employed for recording with said vertical magnetic recording mode.
The existing vertical magnetic head as shown in FIG. 1 comprises a main magnetic pole 3 comprising magnetic film having high magnetic permeability and arranged so as to be confronted with magnetic layer 2 performing the recording in recording medium 1, auxiliary magnetic pole 4 comprising a magnetic material and arranged so as to be confronted through said intervening magnetic medium 1 with said main magnetic pole 3 and coil 5 wound around said auxiliary magnetic pole 4, thereby passing magnetic fluxes 6 issued from auxiliary magnetic pole 4 being exited by means of coil 5 through base 7 defined on the rear surface of said recording medium and through layer 8 having high magnetic permeability and magnetic layer 2 to be converged to said main magnetic pole 3 so that the vertical magnetic recording can be performed by forming the residual magnetization in the direction of thickness of said magnetic layer 2. In this figure the moving direction of the recording medium 1 is shown by arrow A.
However, since such a vertical magnetic head comprises an open path, it is affected by external noise and a diamagnetic field induced in main magnetic pole 3 and auxiliary magnetic pole 4. Since it has a structure having a large clearance between highly magnetic permeable layer 8 playing a roll in converging magnetic fluxes 6 to main magnetic pole 3 and auxiliary magnetic pole 4, the magnetic resistance becomes higher and the efficiencies for recording and reproducing are reduced. In addition, recording medium 1 is sandwiched between main and auxiliary magnetic poles, 3 and 4, so that the recording and reproducing cannot be performed from one side of recording medium 1 as in the conventional magnetic disk and magnetic tape resulting in the complicated head structure and also in the complicated mechanism for displacing the head in a direction perpendicular to the moving direction of recording medium 1 for attaching and detaching the recording medium.
In order to solve such problems, there has been provided a vertical magnetic head capable of recording and reproducing from one side of recording medium 1 as shown by another existing magnetic head as shown in FIG. 2.
In FIG. 2, the magnetic head comprises main magnetic pole 11 arranged so that the tip surface of pole 11 faces magnetic layer 2 of recording medium 1, auxiliary magnetic pole 13 installed so that the tip of pole 13 is apart from the pole 11 by a relatively large gap 12 and coil 14 is wound around said main magnetic pole 11, thereby inducing magnetic flux 15 from main magnetic pole 11 by coil 14. Magnetic flux 15 passes through magnetic layer 2 facing the tip of main magnetic pole 11 and through layer 8 having high magnetic permeability and through the magnetic path passing through magnetic layer 2 again to be converged into auxiliary magnetic pole 13 to perform the residual magnetization in the direction of the thickness of magnetic layer 2 of recording medium 1 moving in the direction of arrow A to perform the vertical magnetic recording.
Different from the first existing embodiment, in the second existing embodiment, the magnetic flux 15 arriving at auxiliary magnetic pole 13 from main magnetic pole 11 through recording medium 1 passes through auxiliary magnetic pole 13 and the joined portion with said auxiliary magnetic pole 13 to be returned to main magnetic pole 11 to define a closed magnetic path.
Accordingly, the recording and reproducing can be performed at one side in the second embodiment and a closed magnetic path is formed during the recording and reproducing so as to reduce external noise. The magnetic head is not affected severely by external noise and has relatively higher recording and reproducing efficiencies.
It should be noted, however, that since main magnetic pole 11 is excited, the density of magnetic flux 11 is higher at the portion at the vicinity of coil 14 than the tip of main magnetic pole 11 and the magnetic flux partially leaks, thus reducing the magnetic flux effective for the recording and reproducing. In addition, since main magnetic pole 11 and auxiliary magnetic pole 13 are attached in parallel to the moving direction A of recording medium, horizontal magnetic flux (represented by 15') is induced in the moving direction of A at the tip portion of main magnetic pole 11 to reduce the recording density. In addition, the gap 12 between main magnetic pole 11 and auxiliary magnetic pole 13 should be relatively large by the above-mentioned reason to extend the magnetic path from main magnetic pole 11 through layer 8 of high magnetic permeability to auxiliary magnetic pole 13 to limit the high efficiencies for the recording and reproducing. Still further, the reproduction is performed including the recorded magnetization on recording medium 1 at the side of auxiliary magnetic pole 13 tending to degrade the S/N ratio.
The embodiment disclosed in Japanese Patent Publication No. 15042/1981 has a structure similar to the second embodiment, so that it has a disadvantage that the S/N ratio tends to be degraded.
The embodiment disclosed in Japanese Patent Publication No. 82318/1977 comprises a magnetic head having the main magnetic pole of thin film prepared by sputtering Permalloy or the like on a glass substrate. Since, however, the structure is similar to the second and third embodiments of prior art, it has a similar disadvantage.
The embodiment disclosed in Japanese Patent Publication No. 42044/1981 has a structure similar to that of first embodiment and a disadvantage similar to that of first embodiment.
The embodiment disclosed in Japanese Patent Publication No. 165918/1981 has a structure similar to that of the third embodiment and the degradation of S/N ratio is prevented by detecting the magnetic flux from the auxiliary magnetic pole during the regeneration by designing to protrude slightly the tip of main magnetic pole from that of auxiliary magnetic pole to contact exclusively the main magnetic pole with the recording medium.
This embodiment has a disadvantage in that since the auxiliary magnetic pole is apart from the recording medium, the output signals is degraded not only in the recording but also in the reproduction.